Heated Glass Element: Description and Operation
GENERAL INFORMATIONAn electrically heated rear window defogger is standard factory-installed equipment on this model. Electrically heated outside rear view mirrors are an available factory-installed option on this model.
REAR WINDOW DEFOGGER SYSTEM
The rear window defogger system will only operate when the ignition switch is in the ON position. When the defogger switch is in the ON position, an electric heater grid on the rear window glass is energized. The electric heater grid produces heat to help clear the rear window glass of ice, snow, or fog.
The defogger system is controlled by a momentary switch in the rear window switch pod installed in the instrument panel lower bezel, which also includes the switch for the rear wiper and washer system. An amber indicator lamp in the switch pod will light to indicate when the defogger system is turned ON. The rear window switch pod also contains the defogger system control circuitry including the timer logic and the defogger relay.
The defogger system will be automatically turned OFF after a programmed time interval of about ten minutes. After the initial time interval has expired, if the defogger switch is turned on again during the same ignition cycle, the defogger system will automatically turn OFF after about five minutes.
The defogger system will automatically shut OFF if the ignition switch is turned to the OFF position, or it can be turned OFF manually by depressing the defogger switch a second time. Following are general descriptions of the major components in the defogger system. Refer to the owner's manual in the vehicle glove box for more information on the features, use and operation of the defogger system.
HEATED MIRROR SYSTEM
The heated mirror system will only operate when the ignition switch is in the ON position. When the rear window defogger switch is in the ON position, an electric heater grid located behind the glass of each of the outside rear view mirrors is energized. When energized, each of these heater grids produce heat to help clear the outside rear view mirrors of ice, snow, or fog.
The heated mirror system is controlled by a momentary rear window defogger switch in the rear window switch pod installed in the instrument panel lower bezel, which also includes the switch for the rear wiper and washer system. An amber indicator lamp in the switch pod will light to indicate when the defogger system is turned on. The rear window switch pod also contains the defogger system control circuitry including the timer logic and the defogger relay.
The heated mirror system only operates in concert with the rear defogger system, and will be automatically turned OFF after a programmed time interval of about ten minutes. After the initial time interval has expired, if the defogger switch is turned ON again during the same ignition cycle, the heated mirror system will automatically turn OFF after about five minutes.
The heated mirror system will automatically shut OFF if the ignition switch is turned to the OFF position, or it can be turned OFF manually by depressing the defogger switch a second time. Following are general descriptions of the major components in the heated mirror system. Refer to the owner's manual in the vehicle glove box for more information on the features, use and operation of the heated mirror system.
REAR GLASS HEATING GRID
The heated rear window glass has two electrically conductive vertical bus bars and a series of horizontal grid lines made of a silver-ceramic material, which is baked on and bonded to the inside surface of the glass. The grid lines and bus bars comprise a parallel electrical circuit.
When the rear window defogger switch is placed in the ON position, electrical current is directed to the rear window grid lines through the bus bars. The grid lines heat the rear window to clear the surface of fog or snow. Protection for the heating grid circuit is provided by a fuse in the Power Distribution Center (PDC).
The grid lines and bus bars are highly resistant to abrasion. However, it is possible for an open circuit to occur in an individual grid line, resulting in no current flow through the line.
The grid lines can be damaged or scraped off with sharp instruments. Care should be taken when cleaning the glass or removing foreign materials, decals, or stickers from the glass. Normal glass cleaning solvents or hot water used with rags or toweling is recommended.
A repair kit is available to repair the grid lines and bus bars, or to reinstall the heated glass terminals.
OUTSIDE MIRROR HEATING GRID
Vehicles equipped with the optional heated mirror system have an electric heating grid located behind the mirror glass of each outside rear view mirror. The heated mirrors are controlled by the rear window defogger switch. Electrical current is directed to the heating grid inside the mirror only when the rear window defogger switch is in the ON position.
If the outside mirror heating grids are both inoperative, see Rear Window Defogger System. If only one of the outside mirror heating grids is inoperative, see Power Mirror System.
The heating grid behind each outside mirror glass cannot be repaired and, if faulty or damaged, the entire power mirror unit must be replaced.
DEFOGGER SWITCH
The rear window defogger switch is integral to the rear window switch pod, which includes the rear wiper and washer switches. The rear window switch pod is installed in the instrument panel lower bezel, which is located near the center of the lower instrument panel, below the heater and air conditioner controls.
The rear window switch pod also contains the rear window defogger logic and timer circuitry, an amber defogger indicator lamp, the rear window defogger relay, and two switch illumination lamps. The indicator and illumination lamps in the switch pod use incandescent bulbs, which can be serviced.
The momentary-type rear window defogger switch provides a hard wired ground signal to the rear window defogger logic and timer circuitry, each time it is depressed. The rear window defogger timer and logic circuitry responds by energizing or de-energizing the rear window defogger relay and the amber defogger indicator lamp, which lights to indicate when the defogger system is turned On. Energizing the rear window defogger relay provides electrical current to the rear window defogger grid.
The rear window switch pod cannot be repaired. If any function of the switch pod except lighting is faulty or damaged, the entire switch pod must be replaced.